The Cisco 3600, 3700, and 3800 Series comprise a product line of modular, multifunction access routers for medium and large-size offices and smaller Internet service providers (ISPs). With more than 70 modular interface options, the Cisco 3600, 3700, and 3800 Series provide solutions for voice and data integration, virtual-private-network (VPN) dial access, and multiprotocol data routing. Using Cisco voice and fax network modules, the Cisco 3600, 3700, and 3800 Series allow customers to consolidate voice, fax, and data traffic on a single network infrastructure. The high-performance, modular architecture of the Cisco 3600, 3700, and 3800 Series protects customers' investment in network technology and integrates the functions of several devices into a single, manageable solution.

The digital modem network modules allow the Cisco 3600, 3700, and 3800 Series to expand their role as multifunction, branch, and enterprise orientated platforms that support voice over data, dial access, and LAN-to-LAN or routing in one modular platform, making it an ideal solution for the "power branch" environment. To provide maximum flexibility in meeting different branch size requirements, the digital modems are available in a variety of densities. Table 1 details the different digital modem options available to Cisco 3600, 3700, and 3800 Series customers. Figure 1 shows the digital modem network module.

Table 1. Different Digital Modem Options Available to Cisco 3600, 3700, and 3800 Series Customer1

The Cisco 3600, 3700, and 3800 Series, installed with the digital modem network modules, offer one of the most flexible, scalable, manageable, and high-performance dial access solutions available in the market today.

The digital modem network modules utilize either the single or dual PRI network module, the 4- and 8-port BRI network modules, or the mixed-media Fast Ethernet and PRI network module (Cisco 3600 only) to support up to 90 remote modem users (using two digital network modules), at speeds up to 56 kbps. Each network module supports up to 30 digital modems. Flexible LAN topologies, including Ethernet, Fast Ethernet, and Token Ring, are supported.

The internal digital modem network module is available with 6, 12, 18, 24, and 30 modems preinstalled, and can also be upgraded on site, from, say, 18 to 24 modems, as simply as upgrading computer memory. This scenario gives the maximum flexibility to grow a dial-in solution as the remote user base grows.

Support for the 56K modem technology allows users to achieve maximum data transfer rates, while still allowing support for V.34 technologies. The modems are software upgradable, and will support future standards as they become available. This high speed ensures the fastest downloads of Web pages and files.

Note: Actual speeds vary, depending on line conditions. Because of FCC limitations, speeds in the United States are less than 56 kbps.

V.92 and V.44 Support

The V.92 and V.44 standards provide consumers and teleworkers what is called a "broadband-lite" Internet experience at dialup prices. V.92 encompasses numerous specifications, including "Quick Connect," which dramatically improves how quickly users can connect with their ISP or a branch office, and "modem on hold," which enables users to suspend and reactivate their dialup connection to either receive or initiate a telephone call. This can be a tremendous productivity enhancement for teleworkers because they do not have to waste valuable time dialing back into
a central site every time they get a phone call.

V.44 technology provides a new standard for compressing data. When compared to V.42, throughput is increased 20 to 60 percent because of a new compression algorithm that is optimized for typical Web content. Of all the new features, V.44 is the only one that speeds the delivery of Web pages to the end user.

Note: The V.92 standard also includes support for pulse code modulation (PCM) upstream, which boosts the upstream data rates from the user. However, PCM upstream is not supported on the digital modem network modules because of limitations in the Modem ISND Channel Aggregation (MICA) modem technology.

Single Solution for Modem and ISDN Callers

The Cisco 3600, 3700, and 3800 can take incoming ISDN or voice calls and automatically switch them to the appropriate internal circuitry. The PRI and BRI switching is based on Q.931 messaging in the ISDN D channel. This out-of-band signaling channel provides a way for the telephone network to label each call as to the type of call. Specifically, when an incoming call is labeled "voice" by the telephone network, the Cisco 3600, 3700, and 3800 direct it to one of its modems. When a call is labeled "ISDN data," it is directed to one of its High-Level Data Link Control (HDLC) controllers. The benefits here are one phone number for modem and ISDN users. R2 and CT1 interfaces also support this switching ability.

The installed modems can be utilized by LAN users for dial-out and fax-out applications, utilizing third-party applications such as the one available from Tactical Software. The modems can be assigned as dial in, dial out, or both. Dial-out support allows the LAN users to utilize the modems during the day for outgoing calls, and use the same modems in the evening for incoming calls from home users.

The ever-expanding numbers of remote users can be easily accommodated with the support for Multichassis Multilink PPP, allowing dial-in pools of lines to span numerous Cisco 3600, 3700,
and 3800 routers. Through the use of Layer 2 Forwarding (L2F) technology and Cisco's exclusive Stack Group Bidding Protocol (SGBP), the Cisco 3600, 3700, and 3800 can grow to meet the requirements of the fast-growing and frequently changing dial environments. Because the essential building block is a relatively small investment, enterprises and branch offices can scale from very small to larger installations.

The Cisco IOS Software can help maximize dial bandwidth, utilizing numerous features such as bandwidth on demand and protocol spoofing. These software features directly reduce line usage and reduce the cost associated with a remote access solution.

Lower operating costs are achievable with the set of central management features of the Cisco 3600, 3700, and 3800 Series. The Cisco 3600, 3700, and 3800 and their internal modems can be managed with CiscoWorks Software. In addition, Cisco's configuration management capabilities provide network managers with complete control over network statistics and the ability to configure and tune network operations from a central location. Finally, comprehensive debugging tools in Cisco IOS Software substantially reduce the time and cost associated with problem isolation
and correction.

Cisco's comprehensive support portfolio delivers solutions that enhance the network throughout its life cycle. From design and installation to preventive and scheduled maintenance, to performance optimization, Cisco solutions promote network reliability, efficiency, and flexibility. Designed to function as an integral product component, these programs deliver seamless support. Together, they proactively help organizations sharpen their competitive edge. Through access to the Cisco.com Web site, customers can both use and market expanded functionality and new features as soon as they become available. Moreover, access to Cisco's technical expertise is available around the clock and around the globe. This virtual team of the world's top networking engineers
is equipped to address every need from troubleshooting to network design and planning.

Digital Modem Applications

Historically, branch-office connectivity has been synonymous with connecting the local LAN to a regional or central site. With the rapid growth in mobile computing and telecommuting, more and more branch offices need to add user-to-LAN capabilities.

Using ISDN PRI, ISDN BRI, or Fast Ethernet and ISDN PRI and digital modem network modules, the Cisco 3600, 3700, and 3800 Series provide the ideal functionality for the branch and enterprise offices.

For basic telephone users, both 33.6K and 56K modem calls can be terminated through a PRI or BRI connection into a digital modem network module, including mobile workers and people working from hotel rooms. For teleworkers with access to BRI, the same phone number could be used to connect to the same Cisco 3600, 3700, or 3800, achieving 64 kbps noncompressed, or with Multilink PPP, 128 kbps.

Multiple backhaul options are available to link back to a corporate network, at speeds up to 8 Mbps. Additionally, a slower-speed (T1 or Frame Relay, for example) connection could link the branch to the World Wide Web.

The Cisco 3600, 3700, and 3800 expand the Cisco dial product line, with products from the Cisco 3600, 3700, and 3800 Series, to the Cisco VPN 5000 Series concentrators, making up a broad range of dial solutions targeted at different market segments, including small branch, enterprise, ISPs, telcos, and carriers.

The Cisco 3600, 3700, and 3800 Series are multifunction platforms, with the ability to support dial access, LAN-to-LAN routing, and multiservice functions in the same chassis. The benefits of this multifunction positioning include modularity, scalability, investment protection, and flexibility. The Cisco 3600, 3700, and 3800 multifunction platforms directly address the many varied needs of the power branch environment.

2V.92 and V.44 support is available initially in Cisco IOS® 12.2(11)YT. This support requires Portware (PW) Version 2.9.1.0 on the Cisco 3640 and 3640A, 3660, 3725, 3745, 3825, and 3845. Support for the Cisco 3620 will be added via the sixth Cisco IOS 12.2T release.